It has been required to manufacture semiconductor devices at low cost, and development has been extensively carried out in recent years on elements such as transistors, memory elements, and solar cells which use layers containing organic compounds for control circuits, memory circuits, and the like (refer to Reference 1: Japanese Published Patent Application No. 2006-148080).
Various applications of semiconductor devices having the elements such as transistors, memory elements, and solar cells which use the layers containing organic compounds are expected. And, compact and lightweight semiconductor devices have been developed by using flexible plastic films instead of non-flexible substrates, e.g., glass substrates or silicon wafers.
Since plastic films have low heat resistance, it is necessary to decrease the highest temperature in a process. Therefore, the semiconductor devices are manufactured by forming semiconductor elements over plastic films by an evaporation method or a sputtering method using a metal mask.
Since plastic films have low heat resistance, transistors formed over plastic substrates cannot have as favorable electrical characteristics as transistors formed over glass substrates at present.
Consequently, such a technique is suggested that minute elements formed over a glass substrate by a photolithography step are separated from the substrate and attached to another base material such as a plastic film (refer to Reference 2: Japanese Published Patent Application No. 2003-174153).